The Windows kernel is the core of the operating system. It provides system level services such as device and memory management, allocates processor time to processes and manages error handling. There is a flaw in the way the kernel passes error messages to a debugger. A vulnerability results because an attacker could write a program to exploit this flaw and run code of their choice. An attacker could exploit this vulnerability to take any action on the system including deleting data, adding accounts with administrative access, or reconfiguring the system.

For an attack to be successful, an attacker would need to be able to logon interactively to the system, either at the console or through a terminal session. Also, a successful attack would require the introduction of code in order to exploit this vulnerability. Because best practices recommends restricting the ability to logon interactively on servers, this issue most directly affects client systems and terminal servers.

A patch is available to fix this vulnerability. Please read the Security Bulletins at http://www.microsoft.com/technet/security/bulletin/ms03-013.asp